If you have more than a few routes installed, its best to search to find the route anyway, so type in a few letters and only the route you're looking for is listed.
e.g. to find XYZ Railroad, just click Start Trainz > Driver/Surveyor > type XY
Out of interest, the default was set to Purchased to avoid endless accusations that Trainz was a "scam" because there was only one route and all the other content was missing or had to be purchased.